Institute for Radiation Protection and Nuclear Safety (IRSN)
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The Reduction of Radiological Consequences of design basis and extension Accidents: re-assessment of calculations and main outcomes of the R2CA project
No full textInternational audienceThe 4-year H2020 R2CA (Reduction of Radiological Consequences of design basis and extension Accidents) project was intended to propose guidelines to harmonize the safety analysis methods through the development of generic methodologies for best estimate evaluations of the radiological consequences (RC). It was dedicated to Design Basis Accidents (DBA) and accidents in the Design Extension Condition domain without significant fuel melting (DEC-A). The project addresses a broad scope of LWR designs (BWR, EPR, PWR, VVER) from Gen II, III and III+ focusing on bounding scenarios of Loss Of Coolant Accidents (LOCA) and Steam Generator Tube Rupture (SGTR) transients. The work performed within the project intends to reduce some of the conservatisms currently used in safety studies and/or licensing calculations, which are necessary to help a better quantification and consideration of the potential changes to come in the operation conditions (e.g. increase of fuel burn-up, usage of ATF). In doing so, some potential higher risks exhibited by knowledge improvements (e.g. clad embrittlement through secondary hydriding, increased fission product releases from high-burn-up or MOx fuels, etc.) were also highlighted. Finally, it was beneficial to the development of innovative measures or tools to prevent these accidents (i.e. algorithms, AI based tools, etc.) as well as to strengthen their management. This article summarizes the main outcomes of the R2CA project presenting the most relevant improvements in simulation tools and calculation methodologies therein. LOCA and SGTR calculation results in DBA and DEC-A domains are discussed. In addition, some insights are given on tools/methods that could be further used to increase the NPP safety based on exploratory innovative work performed within the project. Finally, in conclusion, preliminary guidelines are given for a better estimation of the RC of the considered scenarios
L’huile de mulet jaune des Imrâguens du Banc d’Arguin en Mauritanie : un exemple de transfert des acides gras polyinsaturés des diatomées vers le poisson, au sein de la chaîne alimentaire.
No full textInternational audienceThe Banc d’Arguin National Park (PNBA) in Mauritania is listed by the UNESCO World Heritage. It is characterized by an exceptionnal marine biodiversity with numerous endemic species and it provides a major site of reproduction for western Africa fish. The Imrâguens form fisherman communities established at Banc d’Arguin, who live upon fishing the yellow mullet ( Mugil cephalus ) during its migration and derived products. The fish oil produced by Imrâguens from mullet heads is rich in omega 3 polyunsaturated fatty acids (37.7 % of total fatty acids). The main fatty acid is eicosapentaenoic fatty acid (EPA ; 20.18 ± 0.01 %). This fatty acid is particularly abundant in diatoms, that contribute to 20- 30% of mullet feeding. The identification of 16:4n-1 also provide a good trophic marker for yellow mullet feeding on diatoms. The lipases potentially involved in the mobilization of these fatty acids in the course of digestion of diatoms were identified from the analysis of Mugil cephalus genome. Genes encoding a lipase homologous to gastric lipase and four lipases homologous to pancreatic carboxylester hydrolase or bile-salt stimulated lipase were identified. These later could be involved in the lipolysis of galactolipids, the main lipids present in diatom photosynthetic membranes which are rich in EPA. These data provide an added value to the traditional fishing practice of Imrâgens and highlight the nutritional value of the fish oil they produce.Le Banc d’Arguin est un Parc National Mauritanien (PNBA) inscrit au patrimoine mondial de l’UNESCO. Il présente une biodiversité marine exceptionnelle avec de nombreuses espèces endémiques et son écosystème constitue un site de reproduction majeur pour les poissons de l’Afrique de l’Ouest. Les Imrâguens sont des communautés maritimes établies au Banc d’Arguin qui pratiquent la pêche au mulet jaune ( Mugil cephalus ) lors de sa migration et vivent de sa transformation. L’analyse de l’huile extraite des têtes de mulet jaune par les Imrâguens montre une composition riche en acides gras polyinsaturés de la série oméga 3 (37,7 % des acides gras totaux). L’acide gras majoritaire est l’acide eicosapentaénoïque (EPA ; 20,18 ± 0,01 %). Cet acide gras est particulièrement abondant chez les diatomées, qui constituent 20 à 30% de l’alimentation de ce poisson. L’identification de 16:4n-1 constitue également un marqueur trophique de l’assimilation des acides gras des diatomées par le mullet jaune. Les lipases potentiellement responsables de la mobilisation de ces acides gras au cours de la digestion des lipides de diatomées ont été identifiées par une analyse du génome de Mugil cephalus . Celui-ci code pour une lipase homologue à la lipase gastrique et pour quatre lipases homologues à la carboxylester hydrolase pancréatique ou lipase dépendante des sels biliaires. Ce sont ces dernières enzymes qui pourraient être impliquées dans la lipolyse des galactolipides, constituants des membranes photosynthétiques des diatomées et riches en EPA. Ces résultats mettent en valeur la pêche artisanale pratiquée par les Imrâgens et la qualité nutritionnelle de l’huile de poisson qu’ils produisent à partir du Mulet jaune
Réponse au Stress Environnemental dans les zones d’Exclusion de Tchernobyl et Fukushima : Étude des Effets des Rayonnements Ionisants sur les Individus et les Populations
No full textThis HDR thesis integrates both my studies on understanding the stress response induced by ionizing radiation on the central nervous system at the individual level, and my more recent work on understanding the impacts of nuclear accidents on wild populations. To do this, I use a mechanistic approach using the zebrafish (Danio rerio) as an animal model, and a more ecological approach focusing on sentinel speciesof anurans in the Hylidae family, tree frogs. I also aim to show how current molecular biology tools continue to revolutionize the field of ecotoxicology, by enriching classical methods for studying the effects of pollutants in the environment. This is not intended as a plea for one method over another, but rather to show, if proof were needed, that they provide a better understanding of the evolutionary forces at play when studying the complex interactions between living organisms and their environment. In addition, my research involve the integration of heterogeneous data using systems biology and holistic methods such as transcriptomics and genomics. One of the main themes of this HDR will therefore be the use of these methods to:i) explore the response to neurotoxic stress induced by ionizing radiation using the zebrafish animal model.ii) understand micro-evolutionary processes under real-life exposure conditions to radioactive pollution in the Chernobyl and Fukushima exclusion zones on tree frog populations
Publications reveal how socio-ecological research is implemented: lessons from the Rhône Long Term Socio-Ecological Research platform
No full textInternational audienceSocio-ecological research enlists inter- and transdisciplinarity to address complex environmental issues. Yet the “socio-ecological system” concept can be interpreted in many different ways. A characterization of the diverse practices in socio-ecological research could facilitate dialogue between researchers about the possible conceptual and ethical approaches. In this study, we investigated if a detailed analysis of scientific articles would reveal the nature and course of a socio-ecological research network, and the research angle of its members. The example we used was the Rhône River Long-Term Socio-Ecological Journal Pre-proof Research (LTSER) platform in France. We combined a multivariate analysis of a reading grid of publications by Rhône River LTSER researchers and a textual analysis of the scientific narratives. The publications were from a 10-year period and corresponded to those used in a recent international comparative analysis of LTSER platforms. The analysis revealed that the research was dominated by a biophysical approach, with a progressive increase in social aspects. The emergence of a transdisciplinary approach, co-constructed with operational partners, was also shown. The research conducted by the Rhône River LTSER was grounded in the context of managing a river with strong anthropic influences and interests, and the scientific approach aimed to provide knowledge for guiding decisions. Little reference was made in the publications to socio-ecological conceptual frameworks. Beyond the exampleof this LTSER platform, we identified indicators for describing the degree of inter- and transdisciplinarity and the different perceptions of socio-ecological systems. The narrative analysis revealed the angle of the research approach; this method could be used in future studies for a comparison of the diverse approaches of multiple research groups
A toxicokinetic–toxicodynamic model with a transgenerational damage to explain toxicity changes over generations (in Daphnia magna exposed to depleted uranium)
No full textInternational audienceWe used a toxicokinetic–toxicodynamic (TKTD) model to analyze chronic effects, in Daphnia magna exposed to waterborne depleted uranium (DU) for two or three successive generations (F0, F1 and F2). Our aim was to understand how DU toxicity for growth and reproduction increased across generations. For the first time in a TKTD model, we introduced a novel transgenerational damage compartment, whose level was transmitted from parents to progeny upon egg deposition. Various exposure regimes took account of differences in exposure among generations. We used a simplified dynamic energy budget applied to toxicology (DEBtox) including two independent physiological modes of action (pMoA). The first pMoA, a reduction in assimilation linked to internal concentration, was previously confirmed by complementary analyses (direct measurements of carbon assimilation, histological observations of gut epithelium alterations). The second pMoA, an increase in costs for growth and maturation linked to transgenerational damage, was the most likely among three possible pMoA affecting both growth and reproduction. Modelling results showed that internal concentration and transgenerational damage followed strongly different kinetics across generations, suggesting that the two pMoA played very contrasting roles in long-term DU toxicity for D. magna. Internal concentration only increased between generations F0 and F1, showing no further difference between generations F1 and F2. Our model was able to correctly describe and predict DU toxicity data, in all tested generations and concentrations, and provided a mechanistic explanation for the increase in DU toxicity across generations
Thermodynamique appliquée aux accidents graves dans les réacteurs nucléaires
No full textInternational audienceThis article deals with the application of thermodynamics to severe accident studies in nuclear reactors. First, the problems associated with severe accidents will be described. Next, a description of the physical phenomena that can lead to partial or complete core meltdown will be presented. The application of a thermodynamic approach to severe accident studies will then be discussed, starting with a description of the CALPHAD method and its use for modelling binary and ternary systems. The experiments required to build and validate thermodynamic databases will then be discussed. After describing the contents of the TAF-ID and NUCLEA databases, application calculations will be shown. Finally, the prospects for studies on future reactors will be presented
Bayesian identification and estimation of radon-related increased hazard rates of cancer death in the updated French cohort of uranium miners (1946–2014)
No full textInternational audienceObjective : A recent update of the French cohort of uranium miners added seven years of follow-up data. We use these new data to look for new possible radon-related increased risks and refine the estimation of the potential association between cumulative radon exposure and four cancer sites: lung cancer, kidney cancer, brain and central nervous system (CNS) cancer and leukemia (excluding chronic lymphocytic leukemia, which is not radiation-induced). Methods : Several parametric survival models are proposed, fitted and compared under the Bayesian paradigm, to perform new and original exposure-risk analyses. In line with recent UNSCEAR recommendations, we consider time-related effect modifiers and exposure rate as potential effect modifying factors. We use Bayesian model selection criteria to identify radonrelated increased hazard rates. Results : Under the assumption of a linear exposure-risk relationship, we found a substantial evidence for a strictly positive effect of cumulative radon exposure on the hazard rate of death by lung cancer among French uranium miners. Given the current available data under the assumptions of a linear or log-linear exposure-risk relationship, it is not possible to conclude in favour of the absence or the existence of a strictly positive effect of chronic exposure to radon on the hazard rate of death by kidney cancer. Regarding death by brain and CNS cancer, there is a substantial evidence for the absence of radon-related effect. Finally, under the assumption of a log-linear exposure-risk relationship, a small positive radon-related effect appears when looking at the risk of death by leukemia (excluding CLL). Conclusion : This study investigates the existence of radon-related increased risk of death by lung cancer, kidney cancer, brain and CNS cancer and leukemia under a Bayesian framework and assumptions of linear and log-linear exposure-risk relationships. If there is no doubt in the interpretation of the results for lung cancer and brain and CNS cancer, the conclusion is less clear-cut in the case of kidney cancer and leukemia (excluding CLL). A future update of the French cohort, increasing the follow-up time for miners, may help to reach a clearer conclusion for these two cancer sites
Results from the EURAD routes work package - Towards future european collaboration on radioactive waste management -24662
No full textInternational audienceThe ROUTES Work Package (WP) is one of the two strategic studies being conducted as part of theEuropean Joint Programme on Radioactive Waste Management (EURAD) studying waste managementroutes, from cradle to grave, in Europe.The objectives of ROUTES are to (1) provide an opportunity to share experience and knowledge on wastemanagement routes between interested organisations (from different countries, with programmes atdifferent stages of development, with different amounts and types of radioactive waste to manage), (2)identify safety-relevant issues and their R&D needs associated with the waste management routes (cradleto grave), including the management routes of legacy and historical waste, considering interdependenciesbetween the routes, (3) describe and compare the different approaches to characterisation, treatment andconditioning and to long-term waste management routes, and identify opportunities for collaborationbetween member-states. The expected output is the identification of R&D needs and opportunities forcollaboration between member states.The ROUTES WP encompasses a diverse range of tasks, each addressing distinct topics within the wastemanagement domain. The comprehensive exploration has covered the following key areas: “challengingwaste”, waste characterization, waste acceptance criteria, management solutions for Small InventoryMember States (SIMS), shared solutions, incorporating the valuable insights and perspectives of civilsociety. The recommendations are a result of the insights and achievements obtained from the deliverablesand milestones arising from these tasks.In the area of addressing radioactive waste challenges in Europe, the ROUTES WP has produced significantresults besides recommendations. It enabled a comprehensive understanding of challenges related topredisposal issues at the European level as well as enabled to facilitate the sharing of knowledge andtechnologies. It gave an opportunity for underrepresented voices to tackle their own challenges and accesspotential solutions, and offered civil society representatives to bring their own perspective. ThroughWM2024 Conference, March 10 – 14, 2024, Phoenix, Arizona, USA2networking, valuable connections were built that emphasized the importance for Small Inventory MemberStates (SIMS) to work with Large Inventory Member States (LIMS). Moreover, the work has led to theidentification on one hand of potential stakeholders who are tackling similar waste-related challenges, and,on another hand, the identification of potential customers interested in developing innovative treatmentapproaches for such waste.Furthermore, the implemented initiatives have enhanced visibility on crucial topics, such as sharedsolutions. This visibility has created opportunities for partnerships, especially with countries that may lackthe resources to join the European Repository Development Organization (ERDO) association, whichfocuses on advancing shared waste management options including disposals, to get up-to-date informationon the latest developments in this field. By fostering these collaborations, the ROUTES WP aims to promoteglobal cooperation in effectively addressing the complex issue of radioactive waste disposal.Finally, the ROUTES WP enabled the identification of twenty-two recommendations on Research andDevelopment, strategic studies and knowledge management activities for future European collaboration
Geometrical Characterization of an Inorganic Scintillator Detector for Proton Therapy using a Micrometer Scale Ion Beam
No full textInternational audienceThe fabrication process of an Inorganic Scintillator Detector (ISD), grafted at the tip of an optical fiber, is currently under optimization for its application in proton therapy in-vivo dosimetry. The detector signal magnitude under proton irradiation is strongly correlated to the geometry of the detector-sensitive head and must be accurately characterized. This parameter is also essential for detector response calculation using Monte Carlo(MC) simulation. The purpose of this work is to get a luminescence map of the ISD scanned with a 4 MeV H+ microbeam. The beam is tightly focused on a spot with a diameter of 2.2 µm at a distance of 250 µm working distance, or 4.9 µm and 32.5 µm at distances of 1 and 4 mm, respectively. The beam scans the detector in a raster scan mode. The luminescence signal emitted locally by the detector is collected via the optical fiber and measured using a photon counter. The results provide insights into the geometry of the efficient volume of the detector without damage, making this technique particularly suitable for non-destructive characterizatio
Ex vivo skin diffusion and decontamination studies of titanium dioxide nanoparticles
No full textInternational audienceThis study aims to adapt an experimental model based on Franz diffusion cells and porcine skin explants to characterize the diffusion of TiO2 NPs and to compare the efficacy of different cleansing products, soapy water and a calixarene cleansing nanoemulsion compared with pure water, as a function of the time of treatment. While TiO2 NPs tend to form agglomerates in aqueous solutions, a diffusion through healthy skin was confirmed as particles were detected in the receptor fluid of Franz cells using sp-ICP-MS. In the absence of treatment, SIMS images showed the accumulation of TiO2 agglomerates in the stratum corneum, the epidermis, the dermis, and around hair follicles. Decontamination assays showed that the two products tested were comparably effective in limiting Ti penetration, whatever the treatment time. However, only calixarene nanoemulsion was statistically more efficient than water in retaining TiO2 in the donor compartment, limiting retention inside the skin and preventing NP diffusion through the skin when treatments were initiated 30 min after skin exposure. When decontamination was delayed from 30 min to 6 h, the amount of Ti diffusing and retained in the skin increased.This study demonstrates that TiO2 NPs may diffuse through healthy skin after exposure. Thus, effective decontamination using cleansing products should be carried out as soon as possible